Shade analysis device
A shade analysis device includes an accelerometer providing samples that represent an elevation defined by a sighting reference, an electronic compass providing samples that represent an azimuth heading defined by the sighting reference, and a processor under the control of a program included in the shade analysis device, acquiring an array of the samples that represent an azimuth heading and an array of corresponding samples that represent the elevation, in response to tracing with the sighting reference, a skyline at an interface between an open sky and at least one solar obstruction over a range of azimuth headings.
Pursuant to 35 U.S.C. section 119(e)(1), this application for patent claims priority to the filing dates of U.S. Provisional Patent Application Ser. No. 61/183,495 filed 2 Jun. 2009, U.S. Provisional Patent Application Ser. No. 61/187,045 filed 15 Jun. 2009, and U.S. Provisional Patent Application Ser. No. 61/254,645 filed 23 Oct. 2009, all of which are herein incorporated by reference.
BACKGROUND OF THE INVENTIONThe present invention is in the technical field of shade analysis. More particularly, the present invention is in the technical field of tools for the analysis of the sunlight and solar energy that can be captured at a particular geographic location.
Shade analysis includes determining the impact of trees, buildings or other solar obstructions on the amount of sunlight that falls on a given geographic location. Shade analysis typically involves acquiring the profile of the skyline, which is the interface between the open sky and obstructions that block the sun, and determining the position of the sun in the sky relative to the given location versus time and day of the year. With this information it is possible to determine when the location will be shaded by the solar obstructions. From this, statistics such as annual shade factor or other suitable measures of shade analysis may be established.
Existing methods for shade analysis use azimuth and elevation sights of the skyline that are taken using surveying instruments, these sights are then hand drawn on “sun plots” (paper charts that shows the path of the sun at a given latitude), or the sights are manually entered into a computer system where the effect of the solar obstructions can be determined.
Another method of shade analysis uses a device with a fish-eye dome lens that is placed on a level platform and oriented south using a compass. This fish-eye dome lens projects a 360 degree image of the horizon onto the platform, which enables the skyline to be projected and traced onto a paper sun plot chart. The information from the skyline on the sun plot charts can be manually input into a computer program that produces statistics on the amount of solar energy at the location. However, the devices used in this method are bulky and the method is time consuming and error prone.
Enhancements to the above-disclosed method of shade analysis have been made through the use of digital cameras that are held directly over the fish-eye dome lens to acquire a digital image of the horizon. The acquired digital images are downloaded to a separate computer where the pixel data in the digital images are analyzed to extract the skyline. This method has the drawback of requiring the manual configuration of three separate pieces of equipment, which is time consuming. In addition, this equipment is typically bulky and not suitable for rooftop analysis, and depending on the light conditions in which the digital images are acquired, manual editing of the images may be required to get accurate results.
Another method of shade analysis uses a digital camera to capture a series of digital images of the horizon that are referenced to a known compass orientation, and taken at fixed, known tilt angles. The digital images of the horizon are captured and downloaded to a separate computer where software “stitches” the individual images into a panoramic digital image. The pixel data on the panoramic digital image is then analyzed to determine the skyline. However, this method requires that the camera be held at a precise and consistent tilt angle when capturing the digital images, which typically involves using a special tripod attachment. Further, a user that implements this method of shade analysis must ensure that there is overlap between all of the captured images.
Yet another method of shade analysis relies on capturing a digital image of the skyline directly through a digital camera that has a fish-eye lens. Here, the digital camera is held level with the fish-eye lens pointing directly up to the sky, while an azimuth reference for the digital camera is oriented south using a compass. The fish-eye lens projects a 360 degree image onto the digital camera's light sensitive array, which captures the digital image of the sky. The digital image is then analyzed by an internal processor or it is downloaded to an external computer for pixel analysis to determine the skyline. While this method typically provides for highly accurate shade analysis, the method typically relies on a custom fish-eye lens and extensive factory calibration of the fish-eye lens, compass and a level, which may result in a high manufacturing cost.
SUMMARY OF THE INVENTIONEmbodiments of the present invention include an integrated, portable shade analysis device that enables a user to trace the skyline at a given location. Once the skyline is traced, the shade analysis device computes statistics on the light and solar energy that is received at the location. These statistics typically include hours of sunlight, shade factor, available solar energy, optimum position for solar panels, revenue generated from a specified solar installation, or any other suitable measure of shade analysis that represents any of a variety of solar effects at the location. These statistics may be displayed in graphical and/or tabular form for any chosen time period, or the statistics may include a graphic showing an animated sun moving across the skyline over the course of a day, or a plot of hours lost to shading each day of the year due to solar obstructions.
The shade analysis device enables a user to edit the traced skyline to simulate the removal of a solar obstruction, and then re-runs the statistics with the solar obstruction removed. While the shade analysis device is capable of computing the statistics, performing analysis and presenting results, the user-traced skyline or any other data or results are optionally exported to another computer system or device for presentation or further analysis, typically via a wired or wireless communication interface that may be included in the shade analysis device.
Using commonly available astronomical formulas, the shade analysis device calculates the position of the sun relative to the location of the shade analysis device at any given time. By comparing the information on the sun's position with the skyline, the invention performs shade analysis. The effect of a solar obstruction, such as a tree, may result in a significant difference in sunlight at two locations that are only a few feet apart. For example, at one location sunlight may be obstructed only over a very limited time interval, while at another location, just a few meters away, sunlight may be obstructed for the entire month or more. Due to the quick tracing of the skyline and the speed of subsequent processing provided by the shade analysis device, shade analysis may be quickly performed at a number of locations to find the optimum location, for example, to maximize the amount of direct sunlight.
The shade analysis device typically includes a GPS receiver to determine the location of the shade analysis device, an accelerometer for determining elevation or tilt angle, and an electronic compass for determining azimuth heading. The shade analysis device may also include a digital camera and an associated display. The shade analysis device typically includes a program that is implemented as a software application that runs on a smart phone, gaming system, computer, or other portable electronic device. These devices are suitably equipped with sufficient processing resources, memory, and displays to enable an included program to integrate the measurement, computational, and display functions.
According to first embodiments of the present invention, the program included in the shade analysis device enables a user to trace the skyline using a measurement edge of the shade analysis device as a sighting reference. As the skyline is traced with the measurement edge, the shade analysis device stores samples of the elevation and azimuth heading provided by the accelerometer and electronic compass, respectively, in a memory. The program filters or otherwise processes the samples of the elevations and azimuth headings to establish the skyline that is presented to the shade analysis device at the given location.
According to second embodiments of the present invention, the shade analysis device provides a cross-hair on the display for sighting the skyline. Here, the user aims the cross-hairs at the skyline and varies the elevation of the device so as to trace, with the cross-hairs, the skyline presented to the device over a range of azimuth headings. As the user traces the skyline by moving the shade analysis device, the elevations of the sighted points on the skyline at each increment of azimuth heading are stored in the memory.
According to third embodiments of the present invention, the user pans the horizon with the digital camera while capturing images. As the horizon is panned, the program monitors the azimuth heading and automatically captures the images that include the skyline at azimuth headings that are sufficiently small to ensure overlap between the captured images. The elevations and azimuth headings associated with the images are recorded and stored in memory. The captured images may be “photo stitched” together, using commonly available tools. This enables the azimuth heading and elevation at any point on the captured images to be derived from the azimuth heading and elevation corresponding to any of one or more of the captured images.
The present invention can be better understood with reference to the following Figures. The components in the Figures are not necessarily to scale. Emphasis is instead placed upon illustrating the principles and elements of the present invention.
In
User-tracing of the skyline at the location L includes defining a range of azimuth headings which in this example is defined by the line 121 and the line 123 (shown in
The user traces the skyline 112x by moving the shade analysis device 23 at a typical rate of between ten degree and twenty five degrees per second. Alternative sweep rates may also be used, so long as the sweep rate is sufficiently slow to accommodate readings by the accelerometer 2 and the electronic compass 4. The program 18 acquires readings, or samples, from the electronic compass 4 to establish an array 150 of azimuth heading samples and acquires readings, or samples, from the accelerometer 2 to establish an array 152 of corresponding elevation samples to provide a plot of the user-traced skyline 112x that includes the solar obstructions 122, 124, 126, 128 (shown in
To end the user-tracing of the skyline 112x in an alternative example, the user may lower the elevation of the measurement edge 30 of the shade analysis device 23 quickly, for example, at a rate greater than 25 degrees of elevation per second, or the user may lower the elevation of the measurement edge 30 below a negative threshold value, such as negative 20 degrees (i.e. 20 degrees below the horizontal plane that is orthogonal to the Earth's gravity vector 46). The program 18 detects this abrupt lowering of the shade analysis device 23 or the negative elevation as an indication of the end of the user tracing of the skyline 112x, and removes the corresponding samples from the arrays 150, 152 that are acquired after the end of the sweep, indicated as elements 158 in
The program 18 compares the azimuth heading (true bearing) and elevation (angle above level) of the sun at the location L at any given time, to the azimuth heading H and elevation E from the arrays 15, 152, respectively, to calculate the hours of direct sunlight and the hours of shade in any day, or any other suitable measure of shade analysis that represents any of a variety of solar effects at the location L. Alternatively, the program 18 computes this over a full year to determine shade factor, the percentage of direct sunlight lost due to the obstructions, and/or the amount of solar energy that could be captured by a solar panel at that location L. The program 18 alternatively compiles the arrays and analysis results into .pdf or .csv files, or any other of a variety of formats such as for export to a separate computer system (not shown) via the communication port 20 of the shade analysis device 23. These results may also be assigned a name and stored in the memory 16 for later retrieval or for further analysis.
In an alternative example shown in
According to first alternative embodiments of the present invention, the shade analysis device 23 of
According to second alternative embodiments of the present invention, the shade analysis device 23 of
An example illustrates a skyline detection technique where the digital camera 1 has a horizontal field of view 50 equal to 50 degrees, a vertical field of view 40 equal to 100 degrees, with the first image 102 acquired at a heading of 85 degrees and a tilt angle of 30 degrees, and the image resolution is 100×200 pixels. Here, the left of the acquired image 102 has a heading of 60 degrees, and each pixel in a horizontal direction to the right corresponds to a half of a degree of azimuth heading. Similarly, the top of the image 102 is at an elevation of 80 degrees and each pixel in a vertical direction corresponds to a half of a degree of elevation. The program 18 then performs pixel analysis starting at the top of each pixel column and detecting the interface between the open sky or cloud colors, and the solar obstructions 122, 124, 126, 128, that form the skyline 112x. The elevation E and the azimuth heading H at each point detected within the skyline 112x is typically stored in a results array. This skyline detection process is repeated until the last column within the image 102 is processed, which in this example corresponds to an azimuth heading of 110 degrees. Then, the second image 104 is processed in a similar fashion to the first, the difference being that the starting point for the pixel analysis is 110 degrees, which corresponds to an azimuth heading where the first image 102 is finished. Hence, the program 18 finds the reference point 100 within the second image 104 and moves to the left to the column that represents 110.5 degrees. This pixel analysis is performed on the columns of the second image 104, with the points on the skyline 112x within the image 104 being appended to the entries in the results array. This pixel analysis process is repeated for each of the acquired images until all of the images 102, 104, 106, 108, etc. have been processed. This results in the results array holding a representation of the skyline 112x at increments of a degree of azimuth heading. This information may be saved in the memory 16 with a distinct file name for subsequent recall.
Pixel analysis is alternatively implemented with binary search algorithms or any other search methods. The series of images 102, 104, 106, 108, etc. may also be stitched together using commonly available panorama stitching tool prior to analysis.
While the embodiments of the present invention show the shade analysis device at locations L that are in the Northern hemisphere, wherein the sighting references are typically aimed in the southerly direction, the program 18 alternatively accommodates for locations L that are in the Southern hemisphere, wherein the sighting references are typically aimed in the northerly direction.
While the embodiments of the present invention have been illustrated in detail, it should be apparent that modifications and adaptations to these embodiments may occur to one skilled in the art without departing from the scope of the present invention as set forth in the following claims.
Claims
1. A shade analysis device, comprising:
- an accelerometer providing samples that represent an elevation defined by a sighting reference;
- an electronic compass providing samples that represent an azimuth heading defined by the sighting reference; and
- a processor, under the control of a program included in the shade analysis device, acquiring an array of the samples that represent the azimuth heading and an array of corresponding samples that represent the elevation, in response to tracing with the sighting reference, a skyline at an interface between an open sky and at least one solar obstruction over a range of azimuth headings.
2. The shade analysis device of claim 1 wherein the sighting reference is provided by a measurement edge of shade analysis device, and wherein the tracing results from moving the shade analysis device to change the elevation defined by the sighting reference as the shade analysis device is swept over the range of azimuth headings.
3. The shade analysis device of claim 1 wherein the array of samples that represent the azimuth heading and the array of corresponding samples that represent the elevation are acquired while a user of the shade analysis device traces the sighting reference over the interface between the open sky and the at least one solar obstruction over the range of azimuth headings.
4. The shade analysis device of claim 1 wherein the program uses the array of samples that represent the azimuth heading and the array of corresponding samples that represent the elevation to superimpose a plot of the skyline on a sun plot.
5. The shade analysis device of claim 3 wherein the program is enabled to remove one or more solar obstructions of the at least one solar obstruction from the skyline and to provide a shade factor based on the removed one or more solar obstructions.
6. The shade analysis device of claim 3 wherein the program is enabled to provide a shade factor based on the array of samples that represent the azimuth heading and the array of corresponding samples that represent the elevation of the skyline.
7. The shade analysis device of claim 1 further comprising a digital camera that provides the sighting reference on a display.
8. The shade analysis device of claim 7 wherein the sighting reference includes a cross-hair on the display.
9. The shade analysis device of claim 7 wherein the array of samples that represent the azimuth heading and the array of corresponding samples that represent the elevation are acquired while a user of the shade analysis device traces the sighting reference over the interface between the open sky and the at least one solar obstruction over the range of azimuth headings.
10. The shade analysis device of claim 9 wherein the program uses the array of samples that represent the azimuth heading and the array of corresponding samples that represent the elevation to superimpose a plot of the skyline on a sun plot.
11. The shade analysis device of claim 9 wherein the digital camera acquires at least one image while the user traces the skyline at the interface between an open sky and the at least one solar obstruction.
12. The shade analysis device of claim 11 wherein the program is enabled to superimpose the at least one image on a plot of the skyline at the interface between an open sky and the at least one solar obstruction.
13. A method of shade analysis, comprising:
- providing samples that represent an elevation defined by a sighting reference;
- providing samples that represent an azimuth heading defined by the sighting reference; and
- acquiring an array of the samples that represent the azimuth heading and an array of corresponding samples that represent the elevation in response to tracing with the sighting reference over a range of azimuth headings, a skyline at an interface between an open sky and at least one solar obstruction.
14. The method of shade analysis of claim 13 wherein the sighting reference is provided by at least one of a measurement edge of a smartphone, and an icon on a display associated with a digital camera of the smartphone.
15. The method of shade analysis of claim 14 wherein the tracing results from moving the smartphone to change the elevation defined by the sighting reference as the smartphone is swept over the range of azimuth headings.
16. The shade analysis device of claim 13 further comprising receiving the array of samples that represent the azimuth heading and the array of corresponding samples that represent the elevation, and superimposing a plot of the skyline on a sun plot.
17. A shade analysis device, comprising:
- a digital camera providing a sighting reference on a display;
- an accelerometer providing representations of elevations established by aiming the sighting reference;
- an electronic compass providing representations of azimuth headings established by the aiming of the sighting reference;
- a memory storing an array of azimuth heading samples from the electronic compass and an array of corresponding elevation samples from the accelerometer, which depict a skyline traced over a range of azimuth headings that results from aiming the sighting reference at an interface between an open sky and at least one solar obstruction; and
- a processor enabled by a program to provide a plot of at least one of the skyline, a sun plot and one or more images acquired by the digital camera as the sighting reference is aimed at the interface between the open sky and the at least one solar obstruction.
18. The shade analysis device of claim 17 further comprising a GPS receiver providing location information of the shade analysis device to the processor that uses the location information to provide a sun plot.
19. The shade analysis device of claim 18 wherein one or more of the digital camera, the accelerometer, the electronic compass, the memory, the processor, the program, and the GPS receiver are included within a smartphone.
20. The shade analysis device of claim 17 wherein the program is enabled to stitch one or more images acquired by the digital camera to form a panorama of a horizon that includes the interface between the open sky and the at least one solar obstruction.
Type: Application
Filed: Jun 2, 2010
Publication Date: Dec 2, 2010
Inventor: Simon Andrew Mackenzie (Surrey)
Application Number: 12/802,231
International Classification: H04N 7/18 (20060101); H04M 1/00 (20060101); G06F 19/00 (20060101);